This invention relates to the field of organic synthesis and to a process for forming a N,Nxe2x80x2-diarylquinacridone compound comprising the step of reacting a N,Nxe2x80x2-unsubstituted quinacridone compound with a haloaryl compound in the presence of a metal to arylate the N and Nxe2x80x2 positions and form the corresponding N,Nxe2x80x2-diarylquinacridone compound.
N,Nxe2x80x2-diarylquinacridones have become useful materials and have necessitated synthetic methods for preparing them. In U.S. Pat. No. 6,376,107, Heuer et al disclose the preparation of N,Nxe2x80x2-dialkylquinacridones by contacting unsubstituted quinacridones and alkyl halides with a base such as sodium hydride, in a solvent such as dimethylacetamide or dimethylformamide. This is however not extended to the case of aryl halides.
According to Sci Finder, Radl et al, in a series of disclosures (Czech patents 262587 and 261338), disclose the reaction of 4-oxodihydroquinolines (not a quinacridone) with nitroaryl halides with a base such as sodium hydride in a solvent such as dimethylformamide. The disclosure teaches the use of aryl nitrohalides.
Song et al (Org. Letters, 2002, 4, 1623-1626) have shown a reaction in the presence of cuprous chloride and a dione to form diaryl ethers. They did not extend this reaction to nitrogen compounds such as quinacridones. Goodbrand et al (J. Org. Chem., 1999, 64, 670-674) have shown that Ullman condensation can be accelerated in the presence of a ligand; this was applied to the synthesis of simple triaryl amines, not to deactivated amines, such as quinacridones.
It is a problem to be solved to provide a process for the synthesis of N,Nxe2x80x2-diarylacridone compounds that is simple and efficient.
The invention provides a process for forming a N,Nxe2x80x2-diarylquinacridone compound comprising the step of reacting a N,Nxe2x80x2-unsubstituted quinacridone compound with a haloaryl compound in the presence of a metal to arylate the N and Nxe2x80x2 positions and form the corresponding N,Nxe2x80x2-diarylquinacridone compound. The process is simple and efficient.
The invention process is summarized above. The process is useful for synthesizing N,Nxe2x80x2 aryl quinacridone compounds by a simplified process of reacting an N,Nxe2x80x2-unsubstituted quinacridone compound with a haloaryl compound to arylate the N and Nxe2x80x2 positions. The phrase xe2x80x9cN,Nxe2x80x2-unsubstitutedxe2x80x9d means that neither of the nitrogen atoms of the quinacridone are substituted.
The N,Nxe2x80x2-unsubstituted quinacridone compound may be usefully represented by Formula 1: 
where R3 and R4 can be hydrogen, alkyl, aryl, alkoxy, fluorine, chlorine, nitro or cyano groups; R6-R14 can be hydrogen, or halogen such as chlorine or fluorine, nitro, cyano, carboxyl, or groups which may be further substituted such as alkyl including branched or straight chain, such as methyl, trifluoromethyl, ethyl, alkoxy such as methoxy, ethoxy, propoxy, aryl such as phenyl, 2,4,6, trimethylphenyl, naphthyl, biphenyl, aryloxy such as phenoxy, tolyloxy, carbonamido such as acetamido, benzamido, acyl such as acetyl, phenoxycarbonyl, sulfonyl such as methylsulfonyl, phenoxysulfonyl, acyloxy such as acetyloxy, benzoyloxy, N-substituted carbamoyl, N-substituted sulfamoyl, a heterocyclic oxy group or a heterocyclic thio group; and the heterocyclic nitrogen atoms of 1 have no substituents other than hydrogen atoms. When a molecule may have two or more substituents, the substituents may join together to form a ring, such as a fused ring, unless otherwise provided. Conveniently, R3 and R4 may be hydrogen, fluorine, chlorine, methyl, ethyl, propyl, methoxy, ethoxy, phenyl, and R6-R14 may be the same as R3 and R4 plus nitro, trifluoromethyl, cyclohexyl, or cyano groups. One or more of R6 and R7 or R8 and R7 or R8 and R9, or R12 and R13 or R11 and R12 or R13 and R14 can form a fused ring such as a benzene ring, a cyclohexyl ring, or a benzoxazole ring. Desirably, the substituents adjacent to the nitrogen reaction site are hydrogen, or at least one of R4 and R9, and at least one of R11 and R3 is hydrogen.
The haloaryl compound is conveniently a halophenyl compound represented by formula 2: 
In Formula 2, X represents a halogen atom. Formula 2 is suitably a bromoaryl or iodoaryl compound, and desirably an iodoaryl compound; that is, X is suitably iodine or bromine, and desirably iodine. R15 represents hydrogen or one or more substituent groups on the phenyl ring, desirably a substituents having a Hammet""s "sgr" constant at least 0.05 or more positive than the corresponding methyl group (in the same position). Each R15 may independently be hydrogen or may be selected by those skilled in the art to attain the desired properties for a specific application and can include the same substituents broadly described above for R6-R14. Conveniently, R15 can be hydrogen, fluorine, chlorine, methyl, ethyl, propyl, methoxy, ethoxy, phenyl, nitro, trifluoromethyl, cyclohexyl, cyano. Two R15 groups can be joined to form a fused ring with the parent benzene ring. Suitably, R15 can be hydrogen, methyl, ethyl, cyclohexyl, hydroxy, phenyl, methoxy, or ethoxy. Bulky substituents ortho to the halogen are not convenient and it is desirable that at least one of the ortho positions to the halogen be hydrogen.
The amount of the haloaryl compound used, relative to the starting quinacridone as per formula 1, can range from 2-12 equivalents. The resulting product of this process will be an N,Nxe2x80x2-diarylquinacridone compound, represented by N,Nxe2x80x2-diphenylquinacridone compound 3. 
The reaction occurs in the presence of a base. More specifically, the base needed to perform the process is a dissociative base. The term dissociative base herein refers to alkaline substances known in the art to dissociate in certain solvents, and particularly in polar solvents, into discrete cations and anions. Such dissociative bases include, for example, sodium carbonate, trisodium phosphate, alkali metal alkoxides such as sodium tert-butoxide, alkali metal hydroxides such as sodium hydroxide, alkali metal hydrides such as sodium hydride, and tetrabutylammonium ethoxide. Conveniently the base used can be K2CO3, Cs2CO3, sodium tert-butoxide, or sodium hydride suitably in the amount of 2-3 equivalents per quinacridone mole.
The metal used to effect the coupling can be in the metallic form, a metal compound, or a mixture thereof. The metal is conveniently a transition metal. In the metallic form, and typically, the metal can be chosen from copper (Cu) and palladium (Pd). For a metal compound, particularly suitable are certain compounds of copper and palladium. Examples of copper compounds effective for this are. copper(I) iodide, copper(I) chloride, and copper(I) oxide, especially copper iodide. The amount of copper compound used can be a molar equivalent or can be in a catalytic quantity, which is herein defined as an amount of 2 mole % to 5 mole % relative to 1. A mixture of a copper compound and copper metal is desireable. In such a case, the amount of copper metal can be in the range of 1 equivalent to 5 mole % relative to 1. Palladium compounds effective for this coupling can include palladium diacetate, tris(dibenzylidine acetone)dipalladium, bis(triphenylphosphine)palladium dichloride, or tetrakis(triphenylphosphine)palladium. The amount of palladium compound used can be a molar equivalent or desireably can be in a catalytic quantity, which is herein defined as an amount of 2 mole % to 20 mole % relative to 1.
In addition to the above metal compounds, the use of certain ligands can enhance the effectiveness of this reaction by lowering the activation energy level of the reaction by comlexing the metal or metal compound. Such ligands include but are not limited to 1, 10-phenanthroline, 1,2-trans-cyclohexyldiamine, tri(tert-butyl)phosphine, tricyclohexylphosphine, triphenylphosphine, beta-keto carbonyl compounds including dialkyl beta-keto carbonyl compounds and particularly di-tert-butyl beta-keto carbonyl compounds such as 2,2,6,6-tetramethylheptane-3,5-dione, imidazolium ligands, 2-dicyclohexylphosphinobiphenyl, and 2-dicyclohexylphosphino-2xe2x80x2-(N,N-dimethylamino)biphenyl. The appropriate combination of ligand and a particular metal catalyst can be readily determined by those skilled in the art.
This procedure is conveniently carried out in a solvent. Particularly effective solvents are aprotic solvents, including but not limited to, tetrahydrofuran, toluene, xylene, dioxane, dimethylformamide, dimethyl acetamide, N-methylpyrrolidone, and dichlorobenzene. The choice of solvent is dictated by the solubility of the starting material (N,Nxe2x80x2-unsubstituted quinacridone compound 1) and by the temperature required to effect the transformation. Under certain conditions, the reaction can be conducted without an added solvent, but wherein an excess of 2 can serve the function of a solvent.
Under the reaction conditions stated above, the temperature needed to effect the coupling is typically room temperature (20xc2x0 C.) or higher. Conveniently, the reaction can be carried out at higher temperatures with temperatures of at least 1 40xc2x0 C. conveniently employed. The temperature requirements can also be dictated by the nature of the substituents described in Formulas 1 and 2, and thus the solubility of the starting material.
The scheme of the invention is exemplified in the following, to prepare N,Nxe2x80x2-diphenylquinacridone: 
The resulting N,Nxe2x80x2-diarylquinacridone is typically employed by incorporation into a light emitting layer of an OLED device, e.g. as a dopant. As more fully described in U.S. Pat. Nos. 4,769,292 and 5,935,721, the light-emitting layer (LEL) of an organic EL element includes a luminescent or fluorescent material where electroluminescence is produced as a result of electron-hole pair recombination in this region. The light-emitting layer comprises a single material, but more commonly comprises a host material doped with a guest compound or compounds where light emission comes primarily from the dopant and can be of any color. The host materials in the light-emitting layer can be an electron-transporting material, a hole-transporting material, or another material or combination of materials that support hole-electron recombination. Dopants are typically coated as 0.01 to 10% by weight into the host material. Polymeric materials such as polyfluorenes and polyvinylarylenes (e.g., poly(p-phenylenevinylene), PPV) can also be used as the host material. In this case, small molecule dopants like 3 can be molecularly dispersed into the polymeric host, or the dopant could be added by copolymerizing a minor constituent into the host polymer.
An important relationship for choosing a dopant is a comparison of the bandgap potential which is defined as the energy difference between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the molecule. For efficient energy transfer from the host to the dopant molecule, a necessary condition is that the band gap of the dopant is smaller than that of the host material.
Host and emitting molecules known to be of use include, but are not limited to, those disclosed in U.S. Pat. No. 4,768,292, U.S. 5,141,671, U.S. Pat. No. 5,150,006, U.S. Pat. No. 5,151,629, U.S. Pat. No. 5,405,709, U.S. Pat. No. 5,484,922, U.S. Pat. No. 5,593,788, U.S. Pat. No. 5,645,948, U.S. Pat. No. 5,683,823, U.S. Pat. No. 5,755,999, U.S. Pat. No. 5,928,802, U.S. Pat. No. 5,935,720, U.S. Pat. No. 5,935,721, and U.S. Pat. No. 6,020,078.
When used as a light emitting dopant, the N,Nxe2x80x2-diarylquinacridone compound can be unsubstituted or optionally contains on the two aryl groups and the quinacridone nucleus only substituent groups having Hammett""s "sgr" constant values at least 0.05 more positive than that for a corresponding methyl group. Such substituent groups can include up to two substituent groups directly on the carbon members of the quinacridone nucleus, provided that said substituent groups do not form a ring fused to the five-ring quinacridone nucleus. In such a case, N,Nxe2x80x2-unsubstituted quinacridone compound 1 and haloaryl compound 2 are unsubstituted or substituted only with groups having a Hammett""s "sgr" constant at least 0.05 more positive than the corresponding methyl group. The Hammett""s constant measures the relative electron withdrawing ability of a substituent on an aryl ring with more positive values being more electron withdrawing. Values are given in numerous handbooks such as Substituent Constants for Correlation Analysis in Chemistry and Biology, C. Hansch and A. J. Leo, Wiley, New York (1979) and pKa Prediction for Organic Acids and Bases, D. D. Perrin, B. Dempsey, and E. P. Serjeant, Chapman and Hall, New York (1981). Most groups other than alkyl, alkoxy, hydroxy and amine groups satisfy this requirement and are thus permissible substituents, e.g. halogen, aryl, aromatic heterocycle, and fused aromatic or hetercyclic rings. The aryl group substituent can be e.g. phenyl, biphenyl, and naphthyl. Unsubstituted N,Nxe2x80x2-diarylquinacridone is a compound useful in the invention. Conveniently used are dopants where the diaryl groups are diphenyl groups.
When substituent groups are employed, they can suitably include up to two substituent groups on the carbon members of the quinacridone nucleus. Greater numbers do not provide further advantages, are more complicated to synthesize, and tend to adversely affect color.
Unless otherwise specifically stated, use of the term xe2x80x9csubstitutedxe2x80x9d or xe2x80x9csubstituentxe2x80x9d means any group or atom other than hydrogen. Unless otherwise provided, when a group, compound or formula containing a substitutable hydrogen is referred to, it is also intended to encompass not only the unsubstituted form, but also form further substituted with any substituent group or groups as herein mentioned, so long as the substituent does not destroy properties necessary for device utility. Suitably, a substituent group may be halogen or may be bonded to the remainder of the molecule by an atom of carbon, silicon, oxygen, nitrogen, phosphorous, sulfur, selenium, or boron. The substituent may be, for example, halogen, such as chloro, bromo or fluoro; nitro; hydroxyl; cyano; carboxyl; or groups which may be further substituted, such as alkyl, including straight or branched chain or cyclic alkyl, such as methyl, trifluoromethyl, ethyl, t-butyl, 3-(2,4-di-t-pentylphenoxy) propyl, and tetradecyl; alkenyl, such as ethylene, 2-butene; alkoxy, such as methoxy, ethoxy, propoxy, butoxy, 2-methoxyethoxy, sec-butoxy, hexyloxy, 2-ethylhexyloxy, tetradecyloxy, 2-(2,4-di-t-pentylphenoxy)ethoxy, and 2-dodecyloxyethoxy; aryl such as phenyl, 4-t-butylphenyl, 2,4,6-trimethylphenyl, naphthyl; aryloxy, such as phenoxy, 2-methylphenoxy, alpha- or beta-naphthyloxy, and 4-tolyloxy; carbonamido, such as acetamido, benzamido, butyramido, tetradecanamido, alpha-(2,4-di-t-pentyl-phenoxy)acetamido, alpha-(2,4-di-t-pentylphenoxy)butyramido, alpha-(3-pentadecylphenoxy)-hexanamido, alpha-(4-hydroxy-3-t-butylphenoxy)-tetradecanamido, 2-oxo-pyrrolidin-1-yl, 2-oxo-5-tetradecylpyrrolin-1 -yl, N-methyltetradecanamido, N-succinimido, N-phthalimido, 2,5-dioxo-1-oxazolidinyl, 3-dodecyl-2,5-dioxo-1-imidazolyl, and N-acetyl-N-dodecylamino, ethoxycarbonylamino, phenoxycarbonylamino, benzyloxycarbonylamino, hexadecyloxycarbonylamino, 2,4-di-t-butylphenoxycarbonylamino, phenylcarbonylamino, 2,5-(di-t-pentylphenyl)carbonylamino, p-dodecyl-phenylcarbonylamino, p-tolylcarbonylamino, N-methylureido, N,N-dimethylureido, N-methyl-N-dodecylureido, N-hexadecylureido, N,N-dioctadecylureido, N,N-dioctyl-Nxe2x80x2-ethylureido, N-phenylureido, N,N-diphenylureido, N-phenyl-N-p-tolylureido, N-(m-hexadecylphenyl)ureido, N,N-(2,5-di-t-pentylphenyl)-Nxe2x80x2-ethylureido, and t-butylcarbonamido; sulfonamido, such as methylsulfonamido, benzenesulfonamido, p-tolylsulfonamido, p-dodecylbenzenesulfonamido, N-methyltetradecylsulfonamido, N,N-dipropyl-sulfamoylamino, and hexadecylsulfonamido; sulfamoyl, such as N-methylsulfamoyl, N-ethylsulfamoyl, N,N-dipropylsulfamoyl, N-hexadecylsulfamoyl, N,N-dimethylsulfamoyl, N-[3-(dodecyloxy)propyl]sulfamoyl, N-[4-(2,4-di-t-pentylphenoxy)butyl]sulfamoyl, N-methyl-N-tetradecylsulfamoyl, and N-dodecylsulfamoyl; carbamoyl, such as N-methylcarbamoyl, N,N-dibutylcarbamoyl, N-octadecylcarbamoyl, N-[4-(2,4-di-t-pentylphenoxy)butyl]carbamoyl, N-methyl-N-tetradecylcarbamoyl, and N,N-dioctylcarbamoyl; acyl, such as acetyl, (2,4-di-t-amylphenoxy)acetyl, phenoxycarbonyl, p-dodecyloxyphenoxycarbonyl methoxycarbonyl, butoxycarbonyl, tetradecyloxycarbonyl, ethoxycarbonyl, benzyloxycarbonyl, 3-pentadecyloxycarbonyl, and dodecyloxycarbonyl; sulfonyl, such as methoxysulfonyl, octyloxysulfonyl, tetradecyloxysulfonyl, 2-ethylhexyloxysulfonyl, phenoxysulfonyl, 2,4-di-t-pentylphenoxysulfonyl, methylsulfonyl, octylsulfonyl, 2-ethylhexylsulfonyl, dodecylsulfonyl, hexadecylsulfonyl, phenylsulfonyl, 4-nonylphenylsulfonyl, and p-tolylsulfonyl; sulfonyloxy, such as dodecylsulfonyloxy, and hexadecylsulfonyloxy; sulfinyl, such as methylsulfinyl, octylsulfinyl, 2-ethylhexylsulfinyl, dodecylsulfinyl, hexadecylsulfinyl, phenylsulfinyl, 4-nonylphenylsulfinyl, and p-tolylsulfinyl; thio, such as ethylthio, octylthio, benzylthio, tetradecylthio, 2-(2,4-di-t-pentylphenoxy)ethylthio, phenylthio, 2-butoxy-5-t-octylphenylthio, and p-tolylthio; acyloxy, such as acetyloxy, benzoyloxy, octadecanoyloxy, p-dodecylamidobenzoyloxy, N-phenylcarbamoyloxy, N-ethylcarbamoyloxy, and cyclohexylcarbonyloxy; amine, such as phenylanilino, 2-chloroanilino, diethylamine, dodecylamine; imino, such as 1 (N-phenylimido)ethyl, N-succinimido or 3-benzylhydantoinyl; phosphate, such as dimethylphosphate and ethylbutylphosphate; phosphite, such as diethyl and dihexylphosphite; a heterocyclic group, a heterocyclic oxy group or a heterocyclic thio group, each of which may be substituted and which contain a 3 to 7 membered heterocyclic ring composed of carbon atoms and at least one hetero atom selected from the group consisting of oxygen, nitrogen, sulfur, phosphorous, or boron. such as 2-furyl, 2-thienyl, 2-benzimidazolyloxy or 2-benzothiazolyl; quaternary ammonium, such as triethylammonium; quaternary phosphonium, such as triphenylphosphonium; and silyloxy, such as trimethylsilyloxy.
If desired, the substituents may themselves be further substituted one or more times with the described substituent groups. The particular substituents used may be selected by those skilled in the art to attain the desired desirable properties for a specific application and can include, for example, electron-withdrawing groups, electron-donating groups, and steric groups. When a molecule may have two or more substituents, the substituents may be joined together to form a ring such as a fused ring unless otherwise provided. Generally, the above groups and substituents thereof may include those having up to 48 carbon atoms, typically 1 to 36 carbon atoms and usually less than 24 carbon atoms, but greater numbers are possible depending on the particular substituents selected.